DOPPLER GLOBAL VELOCIMETRY. RANGES OF ACCESSIBLE VELOCITIES. PART I: THEORY

摘要

The Doppler Global Velocimetry (DGV) is a method of velocity measurement in fluid flows based on the Doppler effect and on the conversion of frequency shifts into transmission rates by the use of an absorption line filter. This frequency-to-intensity discriminator is a cell of glass filled with iodine vapor, which is located in front of the receptor. The velocity ranges accessible with such an apparatus are then conditioned by the geometrical setup given by the positions of the camera(s) and laser(s) and by the physiognomy of the absorption peak that is considered. In this paper, the authors propose a procedure to find ranges of accessible velocities in the case of a three-velocity components system: three directions of observations and one direction of illumination are fixed. The influence of these parameters on the accessible velocities is studied considering either one point of the studied zone or the whole area of interest.